The present invention relates to a method of forming an integrated circuit and related integrated circuit.
In recent years, the semiconductor industry has been boosting performance of processors by increasing the number of cores in processors (i.e. multi-core processors), based on Moore's law which states that the number of transistors in integrated circuits doubles approximately every two years. Incidentally, this brings challenges to designing a power efficient on-die communication backbone, e.g. a Network-on-Chip (NoC), for delivery of data-bits between the cores and associated memories. It will be appreciated that electrical (metal-based) interconnects have traditionally dominated on-chip communications in modern processors, and insofar satisfy the communication requirements of conventional multi-core processors. However, as a number of cores increases, a power budget allocated to the corresponding multi-core processor then becomes increasingly constrained, not to mention that performance of the processor will also be severely limited due to usage of electrical interconnects, which undesirably suffer from an inherent bandwidth-distance-power trade-off.
New types of interconnects are needed to enable higher scalability for future multi-core processors. Based on literature, optical interconnects are considered to have the potential to overcome the mentioned bandwidth-distance-power trade-off of electrical interconnects. An optical/photonic interconnect generally comprises a light emitting source for generating an information carrier, a modulator for Electrical/Optical (E/O) data transformation, a photodiode for light detection, miscellaneous passive components for light guiding, and peripheral electronic devices for driving and biasing photonic devices. For an optical interconnect, the light emitting source is generally the most important device as it consumes a substantial fraction of the total link power expended. In this respect, existing solutions tend to utilize off-chip lasers as the light emitting source, which however consume a significant amount of power due to their high threshold current. Even when the optical interconnects are used sporadically, power consumption of the lasers remains largely constant because communication data is modulated externally atop of the continuous wavelengths of the lasers, thus resulting in high power consumption by the lasers regardless of an actual amount of data transmission through the optical interconnects.
One object of the present invention is therefore to address at least one of the problems of the prior art and/or to provide a choice that is useful in the art.